A submersible used to take people to view the wreck of the Titanic has gone missing in the Atlantic Ocean.
It is unclear how many people were on board when it went missing.
Small submersibles occasionally take paying tourists and experts to view the wreck of the Titanic, some 3,800m (12,500ft) beneath the ocean surface.
OceanGate Expeditions, a private company that organises deep sea expeditions, confirmed in a statement that it owned the missing submersible and people were on board.
“We are exploring and mobilising all options to bring the crew back safely,” it said on Monday. “Our entire focus is on the crewmembers in the submersible and their families.”
“We are working toward the safe return of the crewmembers,” it added.
The company charges guests $250,000 (£195,270) for a place on its eight-day expedition to see the famous wreck.
It bills the trip on its carbon-fibre submersible as a “chance to step outside of everyday life and discover something truly extraordinary”.
According to its website, one expedition is ongoing and two more have been planned for June 2024.
Map shows the location of the Titanic wreck
The submersible can seat five people, the company says, which usually includes a pilot, three paying guests, and what it calls an “content expert”.
A full dive to the wreck, including the decent and ascent, reportedly takes eight hours in total.
The Titanic sits 3,800m (12,500ft) beneath the surface at the bottom of the Atlantic. It is about 600km (370 miles) off the coast of Newfoundland, Canada.
The passenger liner, which was the largest ship of its time, hit an iceberg on its maiden voyage from Southampton to New York in 1912. Of the 2,200 passengers and crew onboard, more than 1,500 died.
The Titanic has been extensively explored since the wreck was discovered in 1985.
It lies in two parts, with the bow and the stern separated by about 800m (2,600ft). A huge debris field surrounds the broken vessel.
Last month, the first full-sized digital scan of the wreck was created using deep-sea mapping. The scan shows both the scale of the ship, as well as some minute details, such as the serial number on one of the propellers.